Redox reactions microbe mediation

Figure 4.3 Free energy changes in redox reactions mediated by microbes, (a) Oxidation of reduced inorganic compounds linked to reduction of O2. (b) Oxidation of organic matter CH2O linked to reduction of various organic and inorganic oxidants. pH = 7 and unit oxidant and reductant activities except (Mn +) = 0.2mM and (Fe +) = ImM...

Figure 2. Examples of the types of chemical reactions promoted by aquatic microbes, including reductant excretion (1), transplasma membrane electron transport (2), redox reactions involving extracellular solutes (3) and reductants excreted by the cell (3/>), hydrolysis reactions (4), ami nonenzymatically mediated redox reactions (5). The cell wall and membrane are represented by the curved parallel lines and extracellular enzymes by ovals.

A simplified depiction of the marine nitrogen cycie iiiustrating redox and phase transitions mediated by microbes. The boxes contain the nitrogen species and its oxidation number. The arrows represent transformation reactions as foiiows (1) nitrogen fixation, (2) soiubiiization, (3) ammonification,... 

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